Low-dose helical CT projection data restoration using noise estimation / 南方医科大学学报

OBJECTIVE@#To build a helical CT projection data restoration model at random low-dose levels.@*METHODS@#We used a noise estimation module to achieve noise estimation and obtained a low-dose projection noise variance map, which was used to guide projection data recovery by the projection data restoration module. A filtering back-projection algorithm (FBP) was finally used to reconstruct the images. The 3D wavelet group residual dense network (3DWGRDN) was adopted to build the network architecture of the noise estimation and projection data restoration module using asymmetric loss and total variational regularization. For validation of the model, 1/10 and 1/15 of normal dose helical CT images were restored using the proposed model and 3 other restoration models (IRLNet, REDCNN and MWResNet), and the results were visually and quantitatively compared.@*RESULTS@#Quantitative comparisons of the restored images showed that the proposed helical CT projection data restoration model increased the structural similarity index by 5.79% to 17.46% compared with the other restoration algorithms (P < 0.05). The image quality scores of the proposed method rated by clinical radiologists ranged from 7.19% to 17.38%, significantly higher than the other restoration algorithms (P < 0.05).@*CONCLUSION@#The proposed method can effectively suppress noises and reduce artifacts in the projection data at different low-dose levels while preserving the integrity of the edges and fine details of the reconstructed CT images.

Ultrasonographic observation of the breast in early postmenopausal women during therapy with Cimicifuga foetida extract and sequential therapy with estrogen and progestin / 中华医学杂志(英文版)

<p><b>BACKGROUND</b>It is now recognized that Cimicifuga foetida (C. foetida) extract is effective in alleviating menopausal symptoms. But the durations reported were usually short. The aim of this study was to investigate the effects of C. foetida extract therapy and different estrogen and progesterone sequential therapies, on the breasts of early postmenopausal women.</p><p><b>METHODS</b>This was a prospective randomized trial. Ninety-six early menopausal women were recruited and randomly assigned into three groups treated with different therapies for 2 years. Patients were given C. foetida extract in Group A, estradiol valerate and medroxyprogesterone acetate in Group B, and estradiol valerate and progesterone in Group C. Ultrasonography was used to monitor changes in breast during treatment.</p><p><b>RESULTS</b>In comparing breast glandular section thickness before and after 1 and 2 years of treatment, no significant difference was observed in Group A (11.97 ± 2.84 mm vs. 12.09 ± 2.58 mm and 12.61 ± 3.73 mm, P > 0.05); in Group B glandular section thickness had increased significantly (10.98 ± 2.34 mm vs. 11.84 ± 2.72 mm and 11.90 ± 3.33 mm, P < 0.05) after treatment, the same as Group C (11.56 ± 3.03 mm vs. 12.5 ± 3.57 mm and 12.22 ± 4.39 mm P < 0.05). In comparing breast duct width before and after 1 and 2 years of treatment, no significant difference was seen in Group A (1.07 ± 0.19 mm vs. 1.02 ± 0.18 mm and 0.98 ± 0.21 mm, P > 0.05); in Group B the duct width had a downward trend after treatment (0.99 ± 0.14 mm vs. 0.96 ± 0.22 mm and 0.90 ± 0.18 mm, P < 0.05), the same as Group C (1.07 ± 0.20 mm vs. 1.02 ± 0.17 mm and 0.91 ± 0.19 mm, P < 0.05). The nodules detected before treatment had disappeared after 1-year of treatment or exhibited no distinct changes in the three groups. However, new breast nodules had appeared after 2 years of treatment: There was one case in Group A, two cases in Group B and four cases in Group C, with breast hyperplasia after the molybdenum target check.</p><p><b>CONCLUSIONS</b>In early postmenopausal patients, C. foetida extract therapy and estrogen and progesterone therapy at low doses did not increase the incidence of malignant breast tumors.</p>